Also known as MBR (master boot record) threats, the malware infect an area of the hard disk that makes them one of the first things to be read and executed when a computer is turned on. This enables the threats to effectively dodge many security defenses.

In June, Microsoft warned Windows users about a bootkit Trojan known as Popureb, touching off discussions about whether or not infected users were better off completely re-installing Windows.

Infecting the MBR is not a new technique per se; many of the old boot sector viruses from over a decade ago did something similar, the report notes. The difference is modern MBR malware do so much more than just infecting the MBR. It certainly looks as if MBR malware is making a comeback in 2011.